The present invention relates to a disk apparatus, using a ferroelectric thin film as a recording medium, wherein the ferroelectric film is coated on a disk surface.
FIG. 1 is a schematic construction view of a conventional disk apparatus including a laser diode 1 being an optical source; a collimating lens 2 for collimating a laser beam emitted from the optical source 1; a beam splitter 3 for passing the collimated light received from the collimating lens 2 to an objective lens 4 and for passing reflected light from a disk surface and passed through the objective lens 4, toward an optical detector 7; the objective lens 4 for focusing the collimated light received from the beam splitter 3 onto the track of a disk surface up to a diffraction limit wherein the objective lens 4 is positioned by a lens movement mechanisms; a disk 8 on which information is recorded by a pit or optical magnetism; a focusing lens 6 for focusing reflected light, split by the beam splitter 3, onto an optical detector 7; and the optical detector 7 for transforming the light received from the focusing lens 6 into an electric signal.
In the disk apparatus having such a configuration, a laser beam, emitted by the optical source 1, is incident on the optical detector 7 in order to detect pits formed on the surface of the disk 8. That is, as shown in FIG. 2, a disk surface has pits thereon in order to record information. The pits are of a depth of 1/4 of the laser's optical wavelength (.lambda.), i.e., .lambda./4. Only light having an optical path difference of .lambda./2 is split by the beam splitter 3 and reaches the optical detector 7. Thus, the optical detector 7 can detect pits formed on the disk surface.
However, the disk apparatus using such a recording structure requires a separate device for forming the pits, and a separate method therefor, in order to record information on a disk surface. The separate method and device are different to those required from read information from the disk surface. Therefore, only information written and recorded on a disk by a producing company can be utilized, and storage and utilization of individual's information, for instance is difficult.
An optical magnetism type disk apparatus does not need a separate recording device for recording personal information, so convenience is provided, but the price of this technology is very high.